This section provides background information related to the present disclosure which is not necessarily prior art.
A typical food waste disposer of the type that is disposed underneath a sink and is mounted to a drain opening of the sink includes a food conveying section, a motor section and a central grinding section disposed between the food conveying section and the motor section. The food conveying section conveys the food waste to the central grinding section. The grinding section typically has a shredder plate that is rotated relative to a stationary grind ring by an electric motor of the motor section. The motor has a rotor having a rotatable shaft coupled to the shredder plate. The electric motor is typically an induction motor, but may be other types of motors, such as brushless motors, universal motors, switched reluctance motors, and the like.
FIG. 1 depicts a prior art food waste disposer 100, which is described in U.S. Pat. No. 6,854,673. U.S. Pat. No. 6,854,673 is incorporated by reference herein in its entirety. The disposer 100 may be mounted in a well-known manner in the drain opening of a sink using conventional mounting members of the type disclosed in U.S. Pat. No. 3,025,007, which is incorporated herein by reference in its entirety. The disposer includes an upper food conveying section 102, a central grinding section 104 and a motor section 106, which may include a variable speed motor. It should be understood that motor section 106 could also include a fixed speed motor, such as an induction motor. The central grinding section 104 is disposed between the food conveying section 102 and the motor section 106.
The food conveying section 102 conveys the food waste to the central grinding section 104. The food conveying section 102 includes an inlet housing 108 and a conveying housing 110. The inlet housing 108 forms an inlet at the upper end of the food waste disposer 100 for receiving food waste and water. The inlet housing 108 is attached to the conveying housing 110. A rubber o-ring 112 may be used between the inlet housing 108 and conveying housing 110 to prevent external leaks. A sealant bead may also be used instead of the rubber o-ring 112. The sealant bead is preferably composed of a tacky, malleable material that fills any voids between the inlet housing 108 and the conveying housing 110 and tempers any irregularities in the opposing surfaces of the housings. Some suitable malleable materials for the sealant bead include butyl sealant, silicone sealant, and epoxy.
The conveying housing 110 has an opening 114 to receive a dishwasher inlet 116. The dishwasher inlet 116 is used to pass water from a dishwasher (not shown). The inlet housing 108 and conveying housing 110 may be made of metal or injection-molded plastic. Alternatively, inlet housing 108 and conveying housing 110 may be one unitary piece.
The central grinding section 104 includes a grinding mechanism having a shredder plate assembly 118 and a stationary shredder ring 120. In one embodiment, the shredder plate assembly 118 may include an upper rotating plate 122 and a lower lug support plate 124. The upper rotating plate 122 and lower lug support plate 124 are mounted to a rotor shaft 126 of a rotor 184 of motor 180 of motor section 106. A portion of the conveying housing 110 encompasses the grinding mechanism. The grinding mechanism shown in FIG. 1 is a fixed lug grinding system. Alternatively, a moveable lug assembly could be used such as that disclosed in U.S. Pat. No. 6,007,006 (Engel et al.), which is incorporated herein in its entirety by reference. The grinding mechanism could alternatively use both a fixed lug assembly and a moveable lug assembly.
The shredder ring 120, which includes a plurality of spaced teeth 128, is fixedly attached to an inner surface of the conveying housing 110 by an interference fit and is preferably composed of stainless steel but may be made of other metallic material such as galvanized steel. As shown in FIG. 1, ramps 129 formed on the inside wall of the housing 110 may also be used to retain the shredder ring 120 in the housing 110.
In the operation of the food waste disposer 100, the food waste delivered by the food conveying section 102 to the grinding section 104 is forced by lugs 142 on the shredder plate assembly 118 against teeth 128 of the shredder ring 120. Shredder plate assembly 118 may also include tumbling spikes 144. The sharp edges of the teeth 128 grind or comminute the food waste into particulate matter sufficiently small to pass from above the upper rotating plate 122 to below the plate via gaps between the teeth 128 outside the periphery of the plate 122. Due to gravity and water flow, the particulate matter that passes through the gaps between the teeth 128 drops onto a plastic liner 160 and, along with water entering into the disposer 100 via the inlet to the inlet housing 108, is discharged through a discharge outlet 162 into a tailpipe or drainpipe (not shown). To direct the mixture of particulate matter and water toward the discharge outlet 162, the plastic liner 160 is sloped downward toward the periphery side next to the discharge outlet 162. The discharge outlet 162 may be formed as part of a die-cast upper end bell 164. Alternatively, the discharge outlet 162 may be separately formed from plastic as part of the outer housing of the disposer. The outer surface of the discharge outlet 164 allows a tailpipe or drainpipe to be connected to the discharge outlet 162.
An upper end bell 164 separates the central grinding section 104 and the motor section 106. The motor section 106 is housed inside a housing 174 and a lower end frame 176. The housing 174 may be formed from sheet metal and the lower end frame 176 may be formed from stamped metal. The housing 174 and lower end frame 176 are attached to the upper end bell 164 by screws or bolts 178.
The motor section 106 includes motor 180 having a stator 182 and a rotor 184. Stator 182 includes windings 194. The rotor imparts rotational movement to the rotor shaft 126 of rotor 184. The motor 180 is enclosed within the housing 174 extending between the upper end bell 164 and lower end frame 176. The motor 180 may be a variable speed motor as described in U.S. Pat. No. 6,854,673 and controlled by a controller 220. Alternatively, a brushless permanent magnet motor or an induction motor could be used.
The upper end bell 164 may dissipate the heat generated by the motor 180, prevents particulate matter and water from contacting the motor 180, and directs the mixture of particulate matter and water to the discharge outlet 162.
The plastic liner 160 is attached to the die-cast upper end bell 164 by screws or bolts 166. The upper end bell 164 is attached to the conveying housing 110 by screws or bolts 168. To prevent external leaks, a ring bracket 170 and o-ring or seal 172 may be used to secure the connection between the conveying housing 110 and the upper end bell 164.
To align the rotor shaft 126 and, at the same time, permit rotation of the rotor shaft 126 relative to the upper end bell 164, the upper end bell 164 has a central bearing pocket 165 that houses a bearing assembly 200. In one embodiment, the bearing assembly 200 encompasses the rotor shaft 126 and comprises a sleeve bearing 202, a sleeve 204, a rubber seal 206, a slinger 208 and a thrust washer 210. The sleeve bearing 202 is pushed into the smaller portion of the central bearing pocket 165. The sleeve bearing 202 is preferably made of powered metal having lubricating material. The thrust washer 210 is placed on top of the bearing 202. The steel sleeve 204 encompasses the rotor shaft 126 and is positioned above the thrust washer 210 and sleeve bearing 202. The steel sleeve 204 resides on an upper end portion 127 of the rotor shaft 126. The upper end portion 127 is shaped as a double D to receive the shredder plate assembly 118. A bolt 211 is used to hold the shredder plate assembly 118 to the rotor shaft 126. To keep out debris, rubber seal 206 slides over the steel sleeve 204 and rests in a larger portion of the central bearing pocket 165 of the upper end bell 164. Steel cap or slinger 208 is placed on top of the rubber seal 206.
The bottom of the rotor shaft 126 is permitted to rotate relative to the lower end frame 176 by the use of lower bearing assembly 212. The lower bearing assembly 212 includes a housing 214 and a spherical bearing 216. The spherical bearing 216 is preferably made of powdered metal having lubricating material.
Mechanical and electrical (magnetic) imbalances are known problems in the fabrication of electric motors. In some instances, the motor rotors are machined in order to improve the mechanical balance. Some motor manufacturers use in-line electrical testing of the rotors to improve the magnetic balance.
It is desirable to minimize the air gap between the bearing and rotor shaft to reduce bearing noise. In one known technique of improving the clearance between the rotor shaft and bearing, the rotor shafts are ground to very tight tolerances and the bearings used also have very tight tolerances. A secondary burnishing operation may also be performed on the bearings to improve the consistency of the inside diameter after assembly.